The present invention relates generally to audio and video technology, and more particularly to automatic volume control.
Automatic volume control technology is gaining popularity for use with various types of electronic equipment, when there is a desire to adjust the volume of sound-emitting equipment, i.e.xe2x80x94televisions and audio equipment, based on the noise levels which exists in the immediate surrounding area. An example of this technology can be seen in U.S. Pat. No. 5,666,426 entitled xe2x80x9cAutomatic Volume Control to Compensate for Ambient Noise Variationsxe2x80x9d. The ""426 patent describes an apparatus and method wherein a processing circuitry comprises a microphone for monitoring the ambient noise, an analog-to-digital (xe2x80x9cA/Dxe2x80x9d) converter connected to the output of the microphone, and a digital signal processor connected to the output of the A/D converter. Utilizing this equipment, the processing circuitry calculates the ratio of the equipment""s sound level to the noise level of the ambient environment, polls the room periodically to obtain subsequent ratios, and adjusts the sound level of the equipment depending on whether there has been a change in the ratio.
One disadvantage of existing automatic volume control technology is that a sound-emitting device, not equipped with automatic volume control technology, must be physically modified in order to gain automatic volume control capability. In other words, the automatic volume control equipment must be imbedded in each and every sound-emitting device. Physically modifying each existing device to add automatic volume control capability, in addition to being costly, creates a risk that the existing devices will be damaged. In addition, the manufacturer""s warranties on the sound-emitting device can be voided, since many of the warranties prohibit modification of the device. Thus, owners of existing sound-emitting devices could be discouraged from adding automatic volume controls to their devices.
Another disadvantage of the existing automatic volume control technology is that, by being imbedded in the sound-emitting device, the microphones measure the noise levels near the sound-emitting device even though the person listening to the sound-emitting device is across the room. For instance, if the person using an existing sound-emitting device is watching television while a vacuum cleaner is operating across the room, the automatic volume control apparatus would be performing a noise ratio analysis based upon the noise levels in the vicinity of the television. In the vicinity of the television, the noise generated by the television is significantly greater than the noise generated by the vacuum cleaner several feet away. Thus, the ratio calculated by the automatic volume control apparatus would not accurately reflect the actual noise ratio experienced by the person listening to the device.
Therefore, there exists a need for an automatic volume control device and a method which effectively adjusts the volume of a sound-emitting device based on an ambient noise level in the vicinity of the listener.
There also exists a need for an automatic volume control device and a method which can be utilized with an existing sound-emitting device which accepts a remote signal, and which can be used to control multiple sound-emitting devices without requiring modification of each individual device.
The present invention consists of an automatic remote control device and method which compensates for ambient, environmental noise changes and sudden changes in program material volume. The microphones and circuitry associated with the volume control apparatus are located in an autonomous portable remote control unit that will work with any existing audio/video device that is configured to respond to a remote control input. The remote control device comprises a microprocessor, at least one directional microphone for receiving a sound level emitted from a sound-emitting device, and at least one omni-directional microphone for receiving the total noise level in the vicinity of the remote control device. In one embodiment of the invention, the microprocessor located in the remote control device utilizes the received sound level and the total received noise level to calculate a reference sound-to-noise ratio. If a volume up/down control is pressed by the operator, the remote control device sends the appropriate signal to the sound-emitting device to increase or decrease the sound level, and a new reference sound-to-noise ratio is calculated. If the volume up/down control has not been used, a timed polling loop periodically measures the sound level and the total received noise level so as to calculate a current sound-to-noise ratio and to determine whether the sound-to-noise ratio has changed. If the sound-to-noise ratio has changed, then the remote control device sends the appropriate signal to the sound-emitting device to adjust the sound level so that the original sound-to-noise ratio is maintained. Hysteresis, in which the device determines whether a pre-determined amount of time has passed since the device last adjusted the sound level, is preferably utilized to prevent continuous fluctuations of the sound.